In your case the engine braking made up for, what sounds to be, a poorly calibrated braking system. Yes, front brakes take the majority of braking load and the

In your case the engine braking made up for, what sounds to be, a poorly calibrated braking system. Yes, front brakes take the majority of braking load and they are designed that way from a braking distribution standpoint. But you have zero advantage with engine braking in a 4WD system vs properly calibrated brakes because on snow it doesn't matter - it simply comes down to the point where you lose tire tire friction greater than the inertia of the vehicle. ABS works to prevent a lockup of the wheel which reduces the opportunity to use friction even friction has been lost. You are right that some 4WD systems (generally not AWD systems) can have an advantage of engine braking in wet or snowy conditions by not having to use brakes as much. Most drivers overcompensate on braking application in snow or a loss of control situation, which is why ABS works so well against the natural human response. But if you have a driver that is aware of the vehicle mass and the road conditions a proper braking system wouldn't lose out to control of a vehicle being stopped to engine braking in a 4WD system. Most people don't have the driving skill to know when engine braking would even be advantageous over wheel braking. And engine braking done too aggressively is hard to quickly disengage comparative to letting up on too much wheel brake application which can lead to longer periods of loss of control. Ultimately what Porsche lays claim to is outlandish in extreme situations. They can't beat the laws of physics. And unless their car has active tire studding it wouldn't stand a chance against a quarter mile stretch of wet ice at 4 degree decline. Doesn't matter what vehicle, tires or software you've got. That vehicle is sliding to the bottom with no control.